A case study of a new code generation technique for compilers

Recent developments in optimizing techniques have allowed a new design for compilers to emerge.Such a compiler translates the parsed source code into lower level code by a sequence of steps.Each step expands higher level statements into blocks of lower level code and then performs optimizations on the result.Each statement has only one possible expansion-the task of tailoring this code to take advantage of any special cases is done by the optimizations.This paper provides evidence that this strategy can indeed result in good object code.The traditionally difficult PL/I concatenate statement was investigated as a detailed example.A set of fairly simple optimizations was identified which allow the compiler to produce good code.More elaborate optimizations can further improve the object code.For most contexts of the concatenate statement, the code produced by a compiler using the expansionoptimization strategy described above compares favorably with the code produced by a conventional PL/I optimizing compiler.